The following relates generally to systems, methods and devices for neuromuscular stimulation, sensing, and recording. Generally, the system may be used to receive thought signals indicative of an intended action and provide electrical stimulation to nerves and/or muscles to effectuate the intended action, thereby bypassing or assisting a damaged or degenerated region/pathway of the nervous system. The devices of the present disclosure are neuromuscular stimulation cuffs, also referred to herein as “neural sleeves,” which deliver stimulation to restore movement to parts of the body not under volitional control due to damaged or degenerated neural regions/pathways from brain or spinal cord injury, stroke, nerve damage, motor neural disease, and other conditions or injuries. The system can also be used in a patient that has some local neural or muscle degeneration for therapeutic or rehabilitation purposes.
Subcutaneous implantable neurostimulation cuffs have been commonly used to block pain and to restore function to damaged or degenerative neural pathways. These implantable cuffs are wrapped around a target nerve and generally include one or more electrodes arranged to stimulate the nerve. By including more than one electrode and/or a different geometry of electrodes, implantable cuffs such as the flat interface nerve electrode (FINE) have been able to achieve stimulation selectivity at the level of individual nerve vesicles.
Transcutaneous neurostimulation cuffs behave similarly to implantable cuffs, however there are important differences. Because the electrodes are placed on the surface of the skin, rather than below it, stimulation often can better target skeletal muscle tissue or muscle groups, rather than peripheral nerves located deeper under the skin. Muscular stimulation may be preferable to stimulating major peripheral nerves, e.g. ulnar, median, radial nerves, as stimulating these nerves may cause a patient to feel a tingling sensation and it is more difficult to effect the desired movement. By increasing the number and layout of electrodes in a neuromuscular cuff, similar to the direction taken with implanted nerve cuff designs, current generation neuromuscular stimulation cuffs have been able to selectively stimulate individual muscles or muscle groups and achieve finer movements such as individual finger flexing and extension.
Flexible-like transcutaneous cuffs have been developed which fit around a human appendage such as a forearm to control the wrist or fingers. These flexible cuffs may include sensors which record muscle activity, or electromyography (EMG) signals, and stimulate in response to the EMG signals. Thin film technologies have also become important in the development of functional electrostimulation (FES) devices. Devices incorporating thin film technology are often based on a polyimide substrate covered by a chromium, gold, or platinum film.
Current transcutaneous neuromuscular stimulation electrodes (or patches) present many limitations. Such neuromuscular patches are typically large (several cm across or more) and have a single electrode (conductive surface). This does not allow selective stimulation of small muscles segments for fine wrist and finger control.
It would be desirable to provide improved devices for neuromuscular stimulation. Flexible sleeves with multiple small electrodes would allow programmable spatial stimulation patterns, which is highly desirable when attempting to restore complex muscular movements through neuromuscular stimulation.